Field of the Disclosure
The present disclosure relates to a liquid ejection head and a method for manufacturing the same.
Description of the Related Art
As a liquid ejection head which ejects a liquid such as ink from an ejection port, a liquid ejection head which ejects a liquid using thermal energy is proposed. The liquid ejection head of this type includes an energy generating element which generates thermal energy in accordance with an electrical signal. The thermal energy causes air bubbles to be generated in the liquid, and the liquid is ejected using the air bubbles. In such a liquid ejection head, a mechanical impact (i.e., cavitation) occurs during growth and disappearance of air bubbles when the liquid is ejected. In order to protect the energy generating element from cavitation, forming an anti-cavitation film to cover the energy generating element is proposed.
In many cases, the anti-cavitation film is formed of an electroconductive metallic material from the viewpoint of intensity. If conduction is established between an electroconductive anti-cavitation film and other electrical wirings and a potential is generated, a charge transfers to the liquid and properties of the anti-cavitation film may be changed (i.e., anodized). As a result, a function as the anti-cavitation film may be impaired. It is therefore important that the anti-cavitation film is insulated from other electrical wirings with an insulating film.
Japanese Patent Laid-Open No. 2003-145770 discloses a method for performing an electric inspection as to whether insulation between an anti-cavitation film and other electrical wirings has been established by applying a voltage to a test pad connected to the anti-cavitation film.
The above disclosed electric inspection is based on the premise that it is performed before a liquid ejection head is completed in a manufacturing process of the liquid ejection head. Specifically, the electric inspection is performed when a print element board is formed with an anti-cavitation film etc. formed on a substrate (wafer). However, even after the electric inspection is performed, the print element board is subject to many processes, such as a wiring process and an assembly process, until the liquid ejection head is completed. Therefore, static electricity may be applied to the print element board or external force may act on the print element board, which may cause conduction to be established between the anti-cavitation film and other electrical wirings. Since the liquid ejection head is used with a liquid filled therewith, it is required to inspect existence of conduction between the anti-cavitation film and other electrical wirings also in a condition in which the liquid ejection head is filled with a liquid. In order to reliably establish insulation of the anti-cavitation film, it is required to perform the electric inspection of the anti-cavitation film in the final form in which the liquid ejection head is completed.